An Owner’s Guide to AC and Heat Repairs

TACL B15309C


FAX 281-466-2249

Spring, Tx





POWER Some basic things you should check on your own, to save a service fee for a simple item. First, make sure all your electrical breakers are on. A power flicker, or a storm can trip a breaker, and shut your system off even though it is still in good condition. Your system has two or more power circuits associated to it. If you have gas heat, there will be a single pole (120v) breaker set aside for the indoor furnace only. It is also usually controlled by a light switch in your attic, that may not be labeled. If this switch is off, nothing will come on.. heat, cool or blower. If you’ve been in the attic getting stuff, and your system went down, there’s a good chance you turned the system off when you switched off “the lights”. Electric heat has one or more larger 2pole (230v) breakers. Often a 60Aand a 30A will combine to handle the large current requirements of electrical heat, but if one of these is off, the blower and ac system controls will shut down too.


The outdoor unit will be on a breaker of it’s own, a two pole (230V) ranging from 25-60A depending on unit size. It will trip more often than the heat breakers, because the compressor can pull high current loads when starting under load, such as when the power flicks on/off quickly. There may also be a breaker inside the disconnect, or electric power box next to the unit. This must be on as well.


A breaker has three positions, ON, OFF and Tripped. If it is tripped, it should be in a center position, or feel “wiggly”. You must turn it all the way off, then flip back to on to reset. If a breaker trips again, call the service guy.


FILTERS:  Make sure your air filters are clean. Heavily clogged filters will cut your system’s capacity in half or more, along with overworking the compressor, or overheating the heat unit.


Also check your THERMOSTAT. If your unit “won’t stop running”, make sure the switch on the thermostat is in the FAN :AUTO position. If in ON position, the indoor blower runs constantly, and your outdoor unit will cycle on/off only. Make sure it’s batteries are good (if it uses them). And, just make sure it is correctly turned on. Some electronic thermostats are not so clear, and some have built in delays, so the unit may take 5 minutes or so to respond to setting changes.


ICE BUILD UP on the indoor coil, or at the outside unit is not normal, but can sometimes occur on an otherwise normally operating system. Symptoms would be  reduced or no air flow through vents, poor cooling, possible water leaking on ceiling, visible ice build up at copper connections in attic, or (later stages) ice buildup to outdoor unit and surrounding compressor. Operator related causes for this can be: Very dirty air filter, operation at too cool a temperature setting (Below 68 or so) for too long, or sometimes operating at a low room setting over a cool evening (outdoor below 70) can freeze a coil.  Treatment is the same. Turn outdoor AC unit off, switch FAN switch on thermostat to ON and let system blow air until it thaws out. You will know when it’s done because air will flow freely from vents, and the ice outside (if any) will drop off the copper and compressor. Switch the system back on, and it may be fine. If it is not cooling well, or repeats within a day, call the service guy. Other common causes are: bad blower motor or capacitor, stuck control relays, or contactors, dirty evaporator coil,  or a  low refrigerant charge.


WATER LEAKS: Water leaks inside your house  are usually clogged drains. The condensate water created by an operating AC system is distilled and pure but mold spores can thrive in the damp cold, and grow a “slime” that will clog the small drain tube. While not so easy to service, they “blow out” without much pressure, but will grow closed within a week or two if not treated to kill the spores. Pouring a cup of bleach down the drain tube  twice a year should prevent this from happening. Some drains stay clear on their own for years, some clog within weeks of start up. Just one of those things. Also available are time release tablets that maintain clean drains. Drain clog preventative tablets should be a part of routine maintenance if you have a service contract. You can attempt to clean out clogged drain yourself, but is probably better left to someone with the experience, and the parts to cut into your drain line on hand. They should add a “vent” or a tee, if you don’t already have one, that provides a future opening to clean out drains and add chemical or tablets without cutting the drain line apart.


Water dripping outside your house is different. If you suddenly see water dripping outside your house from a small pipe that never dripped before, you are seeing a secondary or “emergency” drain in action. This is the drain pan you may see in your attic under the coil, or whole unit. This drain pan should normally be dry, but if the primary drain clogs, the water spills over to the secondary where it drips outside to a noticeable location, to notify you to call your service guy to fix the primary clog. If left alone, the secondary may clog as well, and you will start losing sheetrock ceilings.


CONTROL BOARDS: Keeping with technology, more and more units now use control boards to monitor systems and “lock out” on system errors. While not so common in AC systems, most gas furnaces have boards. If they lock out a system, turning the power off and back on should reset the board, and it will attempt to restart whatever mode it is in. If it locks out again, call the service guy.


HEAT PROBLEMS: Because of the safety issues there is little owner diagnosis recommended for heat systems. Generally, if power is on, gas (if used), propane tanks full (if used), troubleshooting is a job for a trained servicer.  A note: heat pumps will develop ice during normal operation outside, but should automatically turn off and defrost as necessary. Do not panic during this cycle because no heat is running, or if you see ice on the unit during heating cycle.



The bottom breaker is “tripped”

Typical outdoor AC disconnect box

Ice showing from frozen coil

Typical damage from an ignored condensate leak

What to look for in AC repair !

What to look for in heat repairs!

What to look for in AC repair !

What to look for in AC repair !

What to look for in heat repairs!

What to look for in heat repairs!



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